Merge patch series "Support Zve32[xf] and Zve64[xfd] Vector subextensions"

Andy Chiu <andy.chiu@sifive.com> says:

The series composes of two parts. The first part Specifically,
patch 1 adds a comment at a callsite of riscv_setup_vsize to clarify how
vlenb is observed by the system. Patch 2 fixes the issue by failing the
boot process of a secondary core if vlenb mismatches.

Here is the organization of the series:
 - Patch 1, 2 provide a fix for mismatching vlen problem [1]. The
   solution is to fail secondary cores if their vlenb is not the same as
   the boot core.
 - Patch 3 is a cleanup for introducing ZVE* Vector subextensions. It
   gives the obsolete ISA parser the ability to expand ISA extensions for
   sigle letter extensions.
 - Patch 4, 5, 6 introduce Zve32x, Zve32f, Zve64x, Zve64f, Zve64d for isa
   parsing and hwprobe, and document about it.
 - Patch 7 makes has_vector() check against ZVE32X instead of V, so most
   userspace Vector supports will be available for bare ZVE32X.
 - Patch 8 updates the prctl test so that it runs on ZVE32X.

The series is tested on a QEMU and verified that booting, Vector
programs context-switch, signal, ptrace, prctl interfaces works when we
only report partial V from the ISA.

* b4-shazam-lts:
  selftest: run vector prctl test for ZVE32X
  riscv: vector: adjust minimum Vector requirement to ZVE32X
  riscv: hwprobe: add zve Vector subextensions into hwprobe interface
  riscv: cpufeature: add zve32[xf] and zve64[xfd] isa detection
  dt-bindings: riscv: add Zve32[xf] Zve64[xfd] ISA extension description
  riscv: cpufeature: call match_isa_ext() for single-letter extensions
  riscv: vector: add a comment when calling riscv_setup_vsize()
  riscv: smp: fail booting up smp if inconsistent vlen is detected

[Palmer: reorder the first two patches so I can merge the fix, and
rebase this on v6.10-rc1 so it's a little easier to manage.]

Link: https://lore.kernel.org/r/20240510-zve-detection-v5-0-0711bdd26c12@sifive.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Author: palmer-dabbelt

Documentation/arch/riscv/hwprobe.rst

@@ -192,6 +192,21 @@ The following keys are defined:
        supported as defined in the RISC-V ISA manual starting from commit
        d8ab5c78c207 ("Zihintpause is ratified").
 
+  * :c:macro:`RISCV_HWPROBE_EXT_ZVE32X`: The Vector sub-extension Zve32x is
+    supported, as defined by version 1.0 of the RISC-V Vector extension manual.
+
+  * :c:macro:`RISCV_HWPROBE_EXT_ZVE32F`: The Vector sub-extension Zve32f is
+    supported, as defined by version 1.0 of the RISC-V Vector extension manual.
+
+  * :c:macro:`RISCV_HWPROBE_EXT_ZVE64X`: The Vector sub-extension Zve64x is
+    supported, as defined by version 1.0 of the RISC-V Vector extension manual.
+
+  * :c:macro:`RISCV_HWPROBE_EXT_ZVE64F`: The Vector sub-extension Zve64f is
+    supported, as defined by version 1.0 of the RISC-V Vector extension manual.
+
+  * :c:macro:`RISCV_HWPROBE_EXT_ZVE64D`: The Vector sub-extension Zve64d is
+    supported, as defined by version 1.0 of the RISC-V Vector extension manual.
+
 * :c:macro:`RISCV_HWPROBE_KEY_CPUPERF_0`: A bitmask that contains performance
   information about the selected set of processors.
 

Documentation/devicetree/bindings/riscv/extensions.yaml

@@ -381,6 +381,36 @@ properties:
             instructions, as ratified in commit 56ed795 ("Update
             riscv-crypto-spec-vector.adoc") of riscv-crypto.
 
+        - const: zve32f
+          description:
+            The standard Zve32f extension for embedded processors, as ratified
+            in commit 6f702a2 ("Vector extensions are now ratified") of
+            riscv-v-spec.
+
+        - const: zve32x
+          description:
+            The standard Zve32x extension for embedded processors, as ratified
+            in commit 6f702a2 ("Vector extensions are now ratified") of
+            riscv-v-spec.
+
+        - const: zve64d
+          description:
+            The standard Zve64d extension for embedded processors, as ratified
+            in commit 6f702a2 ("Vector extensions are now ratified") of
+            riscv-v-spec.
+
+        - const: zve64f
+          description:
+            The standard Zve64f extension for embedded processors, as ratified
+            in commit 6f702a2 ("Vector extensions are now ratified") of
+            riscv-v-spec.
+
+        - const: zve64x
+          description:
+            The standard Zve64x extension for embedded processors, as ratified
+            in commit 6f702a2 ("Vector extensions are now ratified") of
+            riscv-v-spec.
+
         - const: zvfh
           description:
             The standard Zvfh extension for vectored half-precision

arch/riscv/include/asm/hwcap.h

@@ -81,6 +81,11 @@
 #define RISCV_ISA_EXT_ZTSO		72
 #define RISCV_ISA_EXT_ZACAS		73
 #define RISCV_ISA_EXT_XANDESPMU		74
+#define RISCV_ISA_EXT_ZVE32X		75
+#define RISCV_ISA_EXT_ZVE32F		76
+#define RISCV_ISA_EXT_ZVE64X		77
+#define RISCV_ISA_EXT_ZVE64F		78
+#define RISCV_ISA_EXT_ZVE64D		79
 
 #define RISCV_ISA_EXT_XLINUXENVCFG	127
 

arch/riscv/include/asm/vector.h

@@ -37,7 +37,7 @@ static inline u32 riscv_v_flags(void)
 
 static __always_inline bool has_vector(void)
 {
-	return riscv_has_extension_unlikely(RISCV_ISA_EXT_v);
+	return riscv_has_extension_unlikely(RISCV_ISA_EXT_ZVE32X);
 }
 
 static inline void __riscv_v_vstate_clean(struct pt_regs *regs)
@@ -91,7 +91,7 @@ static __always_inline void __vstate_csr_restore(struct __riscv_v_ext_state *src
 {
 	asm volatile (
 		".option push\n\t"
-		".option arch, +v\n\t"
+		".option arch, +zve32x\n\t"
 		"vsetvl	 x0, %2, %1\n\t"
 		".option pop\n\t"
 		"csrw	" __stringify(CSR_VSTART) ", %0\n\t"
@@ -109,7 +109,7 @@ static inline void __riscv_v_vstate_save(struct __riscv_v_ext_state *save_to,
 	__vstate_csr_save(save_to);
 	asm volatile (
 		".option push\n\t"
-		".option arch, +v\n\t"
+		".option arch, +zve32x\n\t"
 		"vsetvli	%0, x0, e8, m8, ta, ma\n\t"
 		"vse8.v		v0, (%1)\n\t"
 		"add		%1, %1, %0\n\t"
@@ -131,7 +131,7 @@ static inline void __riscv_v_vstate_restore(struct __riscv_v_ext_state *restore_
 	riscv_v_enable();
 	asm volatile (
 		".option push\n\t"
-		".option arch, +v\n\t"
+		".option arch, +zve32x\n\t"
 		"vsetvli	%0, x0, e8, m8, ta, ma\n\t"
 		"vle8.v		v0, (%1)\n\t"
 		"add		%1, %1, %0\n\t"
@@ -153,7 +153,7 @@ static inline void __riscv_v_vstate_discard(void)
 	riscv_v_enable();
 	asm volatile (
 		".option push\n\t"
-		".option arch, +v\n\t"
+		".option arch, +zve32x\n\t"
 		"vsetvli	%0, x0, e8, m8, ta, ma\n\t"
 		"vmv.v.i	v0, -1\n\t"
 		"vmv.v.i	v8, -1\n\t"

arch/riscv/include/uapi/asm/hwprobe.h

@@ -60,6 +60,11 @@ struct riscv_hwprobe {
 #define		RISCV_HWPROBE_EXT_ZACAS		(1ULL << 34)
 #define		RISCV_HWPROBE_EXT_ZICOND	(1ULL << 35)
 #define		RISCV_HWPROBE_EXT_ZIHINTPAUSE	(1ULL << 36)
+#define		RISCV_HWPROBE_EXT_ZVE32X	(1ULL << 37)
+#define		RISCV_HWPROBE_EXT_ZVE32F	(1ULL << 38)
+#define		RISCV_HWPROBE_EXT_ZVE64X	(1ULL << 39)
+#define		RISCV_HWPROBE_EXT_ZVE64F	(1ULL << 40)
+#define		RISCV_HWPROBE_EXT_ZVE64D	(1ULL << 41)
 #define RISCV_HWPROBE_KEY_CPUPERF_0	5
 #define		RISCV_HWPROBE_MISALIGNED_UNKNOWN	(0 << 0)
 #define		RISCV_HWPROBE_MISALIGNED_EMULATED	(1 << 0)

arch/riscv/kernel/cpufeature.c

@@ -188,6 +188,40 @@ static const unsigned int riscv_zvbb_exts[] = {
 	RISCV_ISA_EXT_ZVKB
 };
 
+#define RISCV_ISA_EXT_ZVE64F_IMPLY_LIST	\
+	RISCV_ISA_EXT_ZVE64X,		\
+	RISCV_ISA_EXT_ZVE32F,		\
+	RISCV_ISA_EXT_ZVE32X
+
+#define RISCV_ISA_EXT_ZVE64D_IMPLY_LIST	\
+	RISCV_ISA_EXT_ZVE64F,		\
+	RISCV_ISA_EXT_ZVE64F_IMPLY_LIST
+
+#define RISCV_ISA_EXT_V_IMPLY_LIST	\
+	RISCV_ISA_EXT_ZVE64D,		\
+	RISCV_ISA_EXT_ZVE64D_IMPLY_LIST
+
+static const unsigned int riscv_zve32f_exts[] = {
+	RISCV_ISA_EXT_ZVE32X
+};
+
+static const unsigned int riscv_zve64f_exts[] = {
+	RISCV_ISA_EXT_ZVE64F_IMPLY_LIST
+};
+
+static const unsigned int riscv_zve64d_exts[] = {
+	RISCV_ISA_EXT_ZVE64D_IMPLY_LIST
+};
+
+static const unsigned int riscv_v_exts[] = {
+	RISCV_ISA_EXT_V_IMPLY_LIST
+};
+
+static const unsigned int riscv_zve64x_exts[] = {
+	RISCV_ISA_EXT_ZVE32X,
+	RISCV_ISA_EXT_ZVE64X
+};
+
 /*
  * While the [ms]envcfg CSRs were not defined until version 1.12 of the RISC-V
  * privileged ISA, the existence of the CSRs is implied by any extension which
@@ -245,7 +279,7 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
 	__RISCV_ISA_EXT_DATA(d, RISCV_ISA_EXT_d),
 	__RISCV_ISA_EXT_DATA(q, RISCV_ISA_EXT_q),
 	__RISCV_ISA_EXT_DATA(c, RISCV_ISA_EXT_c),
-	__RISCV_ISA_EXT_DATA(v, RISCV_ISA_EXT_v),
+	__RISCV_ISA_EXT_SUPERSET(v, RISCV_ISA_EXT_v, riscv_v_exts),
 	__RISCV_ISA_EXT_DATA(h, RISCV_ISA_EXT_h),
 	__RISCV_ISA_EXT_SUPERSET(zicbom, RISCV_ISA_EXT_ZICBOM, riscv_xlinuxenvcfg_exts),
 	__RISCV_ISA_EXT_SUPERSET(zicboz, RISCV_ISA_EXT_ZICBOZ, riscv_xlinuxenvcfg_exts),
@@ -280,6 +314,11 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
 	__RISCV_ISA_EXT_DATA(ztso, RISCV_ISA_EXT_ZTSO),
 	__RISCV_ISA_EXT_SUPERSET(zvbb, RISCV_ISA_EXT_ZVBB, riscv_zvbb_exts),
 	__RISCV_ISA_EXT_DATA(zvbc, RISCV_ISA_EXT_ZVBC),
+	__RISCV_ISA_EXT_SUPERSET(zve32f, RISCV_ISA_EXT_ZVE32F, riscv_zve32f_exts),
+	__RISCV_ISA_EXT_DATA(zve32x, RISCV_ISA_EXT_ZVE32X),
+	__RISCV_ISA_EXT_SUPERSET(zve64d, RISCV_ISA_EXT_ZVE64D, riscv_zve64d_exts),
+	__RISCV_ISA_EXT_SUPERSET(zve64f, RISCV_ISA_EXT_ZVE64F, riscv_zve64f_exts),
+	__RISCV_ISA_EXT_SUPERSET(zve64x, RISCV_ISA_EXT_ZVE64X, riscv_zve64x_exts),
 	__RISCV_ISA_EXT_DATA(zvfh, RISCV_ISA_EXT_ZVFH),
 	__RISCV_ISA_EXT_DATA(zvfhmin, RISCV_ISA_EXT_ZVFHMIN),
 	__RISCV_ISA_EXT_DATA(zvkb, RISCV_ISA_EXT_ZVKB),
@@ -468,16 +507,15 @@ static void __init riscv_parse_isa_string(unsigned long *this_hwcap, struct risc
 
 		if (unlikely(ext_err))
 			continue;
+
+		for (int i = 0; i < riscv_isa_ext_count; i++)
+			match_isa_ext(&riscv_isa_ext[i], ext, ext_end, isainfo);
+
 		if (!ext_long) {
 			int nr = tolower(*ext) - 'a';
 
-			if (riscv_isa_extension_check(nr)) {
+			if (riscv_isa_extension_check(nr))
 				*this_hwcap |= isa2hwcap[nr];
-				set_bit(nr, isainfo->isa);
-			}
-		} else {
-			for (int i = 0; i < riscv_isa_ext_count; i++)
-				match_isa_ext(&riscv_isa_ext[i], ext, ext_end, isainfo);
 		}
 	}
 }
@@ -686,8 +724,14 @@ void __init riscv_fill_hwcap(void)
 		elf_hwcap &= ~COMPAT_HWCAP_ISA_F;
 	}
 
-	if (elf_hwcap & COMPAT_HWCAP_ISA_V) {
+	if (__riscv_isa_extension_available(NULL, RISCV_ISA_EXT_ZVE32X)) {
+		/*
+		 * This cannot fail when called on the boot hart
+		 */
 		riscv_v_setup_vsize();
+	}
+
+	if (elf_hwcap & COMPAT_HWCAP_ISA_V) {
 		/*
 		 * ISA string in device tree might have 'v' flag, but
 		 * CONFIG_RISCV_ISA_V is disabled in kernel.

arch/riscv/kernel/head.S

@@ -165,9 +165,20 @@ secondary_start_sbi:
 #endif
 	call .Lsetup_trap_vector
 	scs_load_current
-	tail smp_callin
+	call smp_callin
 #endif /* CONFIG_SMP */
 
+.align 2
+.Lsecondary_park:
+	/*
+	 * Park this hart if we:
+	 *  - have too many harts on CONFIG_RISCV_BOOT_SPINWAIT
+	 *  - receive an early trap, before setup_trap_vector finished
+	 *  - fail in smp_callin(), as a successful one wouldn't return
+	 */
+	wfi
+	j .Lsecondary_park
+
 .align 2
 .Lsetup_trap_vector:
 	/* Set trap vector to exception handler */
@@ -181,12 +192,6 @@ secondary_start_sbi:
 	csrw CSR_SCRATCH, zero
 	ret
 
-.align 2
-.Lsecondary_park:
-	/* We lack SMP support or have too many harts, so park this hart */
-	wfi
-	j .Lsecondary_park
-
 SYM_CODE_END(_start)
 
 SYM_CODE_START(_start_kernel)

arch/riscv/kernel/smpboot.c

@@ -214,6 +214,15 @@ asmlinkage __visible void smp_callin(void)
 	struct mm_struct *mm = &init_mm;
 	unsigned int curr_cpuid = smp_processor_id();
 
+	if (has_vector()) {
+		/*
+		 * Return as early as possible so the hart with a mismatching
+		 * vlen won't boot.
+		 */
+		if (riscv_v_setup_vsize())
+			return;
+	}
+
 	/* All kernel threads share the same mm context.  */
 	mmgrab(mm);
 	current->active_mm = mm;
@@ -226,11 +235,6 @@ asmlinkage __visible void smp_callin(void)
 	numa_add_cpu(curr_cpuid);
 	set_cpu_online(curr_cpuid, true);
 
-	if (has_vector()) {
-		if (riscv_v_setup_vsize())
-			elf_hwcap &= ~COMPAT_HWCAP_ISA_V;
-	}
-
 	riscv_user_isa_enable();
 
 	/*

arch/riscv/kernel/sys_hwprobe.c

@@ -69,7 +69,7 @@ static void hwprobe_isa_ext0(struct riscv_hwprobe *pair,
 	if (riscv_isa_extension_available(NULL, c))
 		pair->value |= RISCV_HWPROBE_IMA_C;
 
-	if (has_vector())
+	if (has_vector() && riscv_isa_extension_available(NULL, v))
 		pair->value |= RISCV_HWPROBE_IMA_V;
 
 	/*
@@ -113,7 +113,16 @@ static void hwprobe_isa_ext0(struct riscv_hwprobe *pair,
 		EXT_KEY(ZICOND);
 		EXT_KEY(ZIHINTPAUSE);
 
+		/*
+		 * All the following extensions must depend on the kernel
+		 * support of V.
+		 */
 		if (has_vector()) {
+			EXT_KEY(ZVE32X);
+			EXT_KEY(ZVE32F);
+			EXT_KEY(ZVE64X);
+			EXT_KEY(ZVE64F);
+			EXT_KEY(ZVE64D);
 			EXT_KEY(ZVBB);
 			EXT_KEY(ZVBC);
 			EXT_KEY(ZVKB);

arch/riscv/kernel/vector.c

@@ -173,8 +173,11 @@ bool riscv_v_first_use_handler(struct pt_regs *regs)
 	u32 __user *epc = (u32 __user *)regs->epc;
 	u32 insn = (u32)regs->badaddr;
 
+	if (!has_vector())
+		return false;
+
 	/* Do not handle if V is not supported, or disabled */
-	if (!(ELF_HWCAP & COMPAT_HWCAP_ISA_V))
+	if (!riscv_v_vstate_ctrl_user_allowed())
 		return false;
 
 	/* If V has been enabled then it is not the first-use trap */